UC Berkeley may be the finest public university in the nation, but the toilets have to be cleaned the same as anyplace else.

The 300 custodians who do the university's scrubbing pointed up this household reality during their recent picketing of graduation ceremonies. Their message: They work for the top-rated public institution of higher learning but earn a below-average wage.

Picketing by the janitors union frustrated six commencement events -- the speakers, including former presidential candidate Howard Dean, refused to cross the janitors' lines -- and rankled Cal at a time of embarrassment over questionable executive pay deals by top officials in the university system.

Dean said workers can't support their families on what Cal pays its janitors.

What makes the dispute unusual is that it's not about workers campaigning for a new contract: The custodians union, Local 3299 of the American Federation of State, County and Municipal Employees, has a new contract, and its members recently received a 4 percent pay increase under it.

And they're due for as much as 8 percent more through 2008.

But union leaders say it's not enough. Cal janitors remain underpaid in comparison with custodians at local California State University campuses and at community college districts in the East Bay.

Although the negotiated pay increases will bring the Cal janitors up to $13 an hour, union leaders say, that's still more than $2 below the industry average.

Union leaders say Cal should start paying its janitors at that level now, using a contract provision that allows the university to make equity-pay adjustments for selected workers.

It's not unusual for the union, which represents 18,000 UC employees statewide, to ask for and receive equity increases -- reflecting local pay rates -- for selected categories of workers during the life of a contract, union organizer Deborah Grabelle said. Such requests are seldom controversial, she said.

But a meeting between the union and UC Berkeley officials in November left the two sides far apart on the question of higher pay for custodians, she said.

"We do pay-equity fights all the time," she said. "We could list in double digits the places where people have gotten equity increases. This is a first in terms of this level of intensity."

Grabelle said the union has no indication the university's position has changed since the meeting seven months ago that led to the picketing.

But UC Berkeley Chancellor Robert Birgeneau broached the issue recently in a letter to the Daily Californian newspaper.

"We are committed to improving the wages of our lowest-paid staff and will continue to seek support for increased public funding to facilitate enhanced salaries for them," he wrote. "I should also note that these issues are negotiated on a systemwide level, not locally, so no individual campus can make significant changes on its own."

UC system spokesman Noel Van Nyhuis said individual campuses can make such changes as long as they are approved after extensive system-wide consultation.

For the union, the campaign for pay equity amid the crisis over UC executive compensation is a chance to talk about the lives of the working poor on campus. One such worker is Maricruz Manzanarez, 37, a single mom with three teens at home in Richmond.

She works at Ehrman Hall, a high-rise south of campus where more than 300 undergraduates live. Her job is to clean four of the eight floors.

Earlier this month, Manzanarez picketed the law school commencement. One student said the pickets disgusted him, but her response was to congratulate him on his success.

Manzanarez takes home $1,700 a month, of which all but $100 goes to rent. Child support from her former husband pays the rest of the bills, except for the months she has to cover with her credit card.

Manzanarez is active in her union and recently took part in a meeting with a university administrator.

"We went over there to have a meeting with management and ask them for a better wage, and we told them that the other universities are paying more than UC Berkeley does," she said. "And the directors told us, 'Let me ask you a question, if it's so beautiful out there, what are we doing here?' "

Manzanarez said that because of her health, she's afraid she might not be able to get a better job with another employer. She showed scars on her right shoulder and both wrists, saying they were from surgeries for repetitive stress injuries.

"After working here and getting all torn apart, who's going to take us?" she asked.

Manzanarez, who became a UC Berkeley custodian seven years ago, wiped, mopped, swept and dusted for two hours one recent Monday, alternately stretching, pushing and bending her body in the process. She seemed slightly winded as her lunch break approached.

"I had cancer in 2001, thyroid cancer," she said. "I had surgery. I'm on life treatment now. I get my pill every morning. Every month I have to get a refill, so I'm there. I'm feeling good, better than I was."

Asked if she felt bad about the pickets upsetting graduation events, Manzanarez said: "It's bad for us to do it to the students, but that's the only way."

This year's dorm residents gave Manzanarez an iPod for a gift and made a giant thank-you note they posted on a wall.

A student named Steve wrote: "Thanks for cleaning our bathroom."

"I can't imagine what Maricruz has to go through because I've never done that kind of labor," said Simon Gutman, a freshman from Santa Cruz. "It's tough work. She's amazing. Maricruz is so humble about it. I think if you ask everybody on this floor, we really appreciate everything she's done."